The topic of animal experimentation, covered in "Saving Animals and People" [SA Perspectives] and "Protecting More than Animals," by Alan M. Goldberg and Thomas Hartung, generated the most heat and light in letters. Readers generally agreed that minimizing or eliminating animal testing wherever possible is a laudable goal; however, it is ethically acceptable to continue animal research if it is the only way to promote advances benefiting humanity. But to some, a "humans first" guideline rang hollow: Richard Dingman of Montague Center, Mass., wrote, "Just what is the 'ethical' basis for declaring that animal experimentation is preferable to testing on humans? The editors assume our acceptance of human superiority has an objective foundation so obvious that it need not be mentioned." The heartfelt debate goes on.